MEDICINE | IN THE LAB

Pets come to the rescue

A new nationwide database of animals could alert us to an impending disease outbreak or a bioterrorism attack.

THAT gentle Lab sleeping blissfully at your feet, those two tabbies grooming each other on the sofa: They could be unlikely recruits to the war on terrorism. Under a new surveillance system developed at Purdue University, pets may provide early warning of an impending epidemic of dangerous diseases such as SARS or avian flu -- or even alert us to a bioterror threat.

That's the intent, at least, of the Purdue program, which uses the computerized database of a nationwide chain of veterinary hospitals to spot disease outbreaks. The rationale: Dogs and cats share a home environment with their owners and are exposed to the same germs. But the pets have a faster metabolism, so they will exhibit disease symptoms sooner than humans. This makes them excellent sentinels for certain so-called zoonotic illnesses -- ones that can spread from animals to humans.

And that's a lot of diseases. Between 65% and 75% of human infections, including SARS, influenza and Lyme disease, originate in animals.

"The issue of emerging zoonotic diseases is huge," says Dominic Travis, a veterinary epidemiologist at Chicago's Lincoln Park Zoo who helped launch the Zoo Network, which is a similar surveillance system for wild animals in captivity. "This database is a great resource."

The National Companion Animal Surveillance Network, as it's called, is the brainchild of Larry Glickman, a veterinary epidemiologist at Purdue University in West Lafayette, Ind.

"We don't know where the next disease is coming from, but it's likely to start in animals," says Glickman. "The exchange of pets across continents is now so great that the opportunity for transmission is tremendous. If we can detect a bacterium or virus that is causing diseases in animals, we could terminate the problem before it jumps to humans."

But, Glickman adds, "to do that we have to be able to monitor clinical signs in animals and know that something had changed, and quickly identify what triggered the change."

The network Glickman created is designed with this in mind. It taps into data from the Banfield pet hospital chain, which is headquartered in Portland, Ore., and has 500 facilities in 44 states. The chain sees about 2% of the nation's cats and dogs -- about 3.5 million pets -- each year. Information about these pets is entered into a nationwide computerized database, which is updated daily with new information from the estimated 70,000 pets that visit the animal hospital chain each week.

Funded with a $1.2-million grant from the U.S. Centers for Disease Control in Atlanta, Glickman devised a special software system to mine Banfield's database. With just a keystroke, scientists can watch the pattern of any illness -- whether it's kennel cough or canine flu -- moving through the pet population, like a wave rippling around a sports arena.

But the software does more than search for ailments that have been diagnosed: It scans the database for certain clinical signs -- sudden blindness, perhaps, or unsteady gait -- so that outbreaks of new or known diseases can be detected. "This adds another layer of protection," explains Hugh Lewis, president of Datasavant, a sister company to the Banfield hospitals and a veterinarian who helped develop the pet network.

It's possible, for example, that the surveillance system would provide the first sign that the Asian bird flu currently in the news had arrived here in the U.S. That's because cats are susceptible to the virus. When the initial epidemic hit in Thailand, thousands of chickens were killed off and their carcasses fed to zoo cats. Tigers caught flu from eating the chicken, and died. "So we know the potential is there for cats and other animals to become part of the flu cycle," says Glickman.

The network's database has already been tapped by the Department of Homeland Security. Last month, Glickman got a call from government officials asking about any unusual sicknesses in dogs and cats in the Washington, D.C., area. The officials had detected a bacterium in the air that causes tularemia, a highly infectious disease that triggers severe respiratory illnesses and can be fatal.

"It coincided with an antiwar demonstration, so it raised all sorts of hackles about what this might mean," says Glickman. "It turned out to be a false alarm."

But, he adds, such a hypothetical attack would be easier to pinpoint now that there are two parallel detection systems -- animals as well as people. "If both show something, then you can be pretty sure something is indeed happening," he says.

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Zoo animals help too

A similar animal surveillance system, the Zoo Network, was launched in 2001 to track the West Nile virus, which first made its presence known in the U.S. in 1999 -- on zoo grounds. Officials at the Bronx Zoo in New York noticed that crows at the zoo were dying from an unexplained inflammation in the brain. The Zoo Network is still focused primarily on monitoring West Nile fever, but plans are underway to expand the system to detect bird flu. "We've built an infrastructure for detecting West Nile outbreaks that hopefully can be applied to avian flu," says Dominic Travis, one of the network's coordinators.